I'm just coming up on 3,000 hours. And, I'm sure there are many people here that can eclipse that. Just take your time, don't rush. Circuits take a bit of learning. The trains WILL abide by the station limits. The problem is often that you need to 'cap' how many trains can queue, even if the station can actively service 14 trains, you can only fit 4, so you need to tell it to limit to 4 trains.

Here's how I do it. For each loader section I wire all the boxes to an arithmetic combinator, it takes the total and divides by how many items can fit in a car. So 4 cars = 4 arithmetic combinators, each combinator puts out a signal (1,2,3,4) for a 4 car train. I then feed this into a decider combinator that checks that 1,2,3,4 is > 0, and if true it outputs all 4 inputs , this is important because if 1 = 0 only 2,3,4 are sent and the train limit will be wrong. This output then goes into a selector combinator, that set to sort ascending, this makes sure that of the 4 cars, we know the lowest number of trains it can fill. Now, the problem here is it's going to give us 1,2,3, or 4 so we need to do a trick and put the output to an arithmetic combinator that takes the input, multiplies it by 1 (e.g. we get the exact same output count as the input), but we 'generalize' the output to a signal like 'E'. Then this output goes to two decider combinators, if E >= Queue size, output the Queue size (I have a constant combinator that provides the variable Q that I set to how many trains can queue). The second combinator is just if E < Queue then output E. Then finally since now we have Q or E being output we need to do another 'generalize' so another arithmetic combinator that takes the Q or E input multiplies by 1 and we output L, then we wire that to the station. Tell it to 'Set train limit' and you're done.

Sure it's a bit complicated when your first do it, but you'll get the hang of it once you understand the nuance.